[Xen-changelog] [xen stable-4.9] viridian: fix cpuid leaf 0x40000003

[patchbot@xxxxxxx]

commit 74fa9552c1e3ef79bd4db0a67fc538bbd61b7561
Author:     Paul Durrant <paul.durrant@xxxxxxxxxx>
AuthorDate: Fri May 18 12:01:31 2018 +0200
Commit:     Jan Beulich <jbeulich@xxxxxxxx>
CommitDate: Fri May 18 12:01:31 2018 +0200

    viridian: fix cpuid leaf 0x40000003
    
    The response to viridian leaf 3 needs to split a 64-bit mask across EAX and
    EBX, with the low order 32 bits in EAX and the high order 32 bits in EBX.
    To facilitate this a union of two uint32_t values and the mask (type
    HV_PARTITION_PRIVILEGE_MASK) is allocated on stack as follows:
    
    union {
        HV_PARTITION_PRIVILEGE_MASK mask;
        uint32_t lo, hi;
    } u;
    
    This, of course, is incorrect as both lo and hi will alias the low order
    32 bits of the mask.
    
    This patch wraps lo and hi in an anonmymous struct to achieve the desired
    effect.
    
    NOTE: Fixing this also stops Windows making the HvGetPartitionId hypercall
          which was previously considered erroneous behaviour. Thus the
          hypercall handler is also modified to stop squashing the
          'unimplemented' warning for this hypercall.
    
    Signed-off-by: Paul Durrant <paul.durrant@xxxxxxxxxx>
    Acked-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
    master commit: 29fc0493d8eabdd63f5bbff9e3069253053addca
    master date: 2018-05-14 12:57:13 +0100
---
 xen/arch/x86/hvm/viridian.c | 8 +++-----
 1 file changed, 3 insertions(+), 5 deletions(-)

diff --git a/xen/arch/x86/hvm/viridian.c b/xen/arch/x86/hvm/viridian.c
index aa9b87c0ab..73df1336d8 100644
--- a/xen/arch/x86/hvm/viridian.c
+++ b/xen/arch/x86/hvm/viridian.c
@@ -245,7 +245,7 @@ void cpuid_viridian_leaves(const struct vcpu *v, uint32_t 
leaf,
         };
         union {
             HV_PARTITION_PRIVILEGE_MASK mask;
-            uint32_t lo, hi;
+            struct { uint32_t lo, hi; };
         } u;
 
         if ( !(viridian_feature_mask(d) & HVMPV_no_freq) )
@@ -966,12 +966,10 @@ int viridian_hypercall(struct cpu_user_regs *regs)
         gprintk(XENLOG_WARNING, "unimplemented hypercall %04x\n",
                 input.call_code);
         /* Fallthrough. */
-    case HvGetPartitionId:
     case HvExtCallQueryCapabilities:
         /*
-         * These hypercalls seem to be erroneously issued by Windows
-         * despite neither AccessPartitionId nor EnableExtendedHypercalls
-         * being set in CPUID leaf 2.
+         * This hypercall seems to be erroneously issued by Windows
+         * despite EnableExtendedHypercalls not being set in CPUID leaf 2.
          * Given that return a status of 'invalid code' has not so far
          * caused any problems it's not worth logging.
          */
--
generated by git-patchbot for /home/xen/git/xen.git#stable-4.9

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